Obstetrics

SOGC CPGs

Physiology of pregnancy

CVS
Cardiac output increases 30-50%, peaking at about 24 wks. CO becomes sensitive to body position. Positions that cause the enlarging uterus to obstruct the vena cava the most (e.g. recumbent position) cause CO to decrease the most. During labor, CO increases another 30%.

Heart rate increases from the normal 70 to as high as 90/min, and stroke volume increases. During the 2nd trimester, BP usually drops (and pulse pressure widens). Pregnancy does not affect the indications for or safety of cardioversion.

Hematologic
Hemodilution → Hb &darr from about 13.3 to 12.1 g/dL. WBC count increases slightly to 9,000 to 12,000/μL. Marked leukocytosis (> 20,000/μL) occurs during labor and the first few days postpartum.

Renal
Progesterone (predominantly) relaxes smooth muscle & pressure from the enlarged uterus on the ureters → hydroureter. Postpartum, the urinary collecting system may take as long as 12 wk to return to normal.

GI
Progesterone relaxes smooth muscle & pressure from the enlarging uterus on the rectum and lower portion of the colon may → constipation. Heartburn and belching are common, possibly resulting from delayed gastric emptying and gastroesophageal reflux due to relaxation of the lower esophageal sphincter and diaphragmatic hiatus hernia. HCl production decreases; thus, peptic ulcer disease is uncommon during pregnancy. Preexisting ulcers often become less severe.

Liver
Placental production of alkaline phosphatase increases during the 3rd trimester and may be 2-3x normal at term. Other routine liver tests are normal.

Endocrine
The placenta produces corticotropin-releasing hormone (CRH) → ↑ maternal ACTH → ↑ aldosterone & cortisol → edema. Increased production of corticosteroids and increased placental production of progesterone & human placental lactogen → insulin resistance. Insulinase, produced by the placenta, may also increase insulin requirements.

Substance	Crosses placenta?	Comment
TSH	no
T3	small	enough to prevent fetal hypothyroidism
T4	small	enough to prevent fetal hypothyroidism
PTU	small	may cause fetal hypothyroidism


Maternal hypothyroidism may → fetal neurological & cognitive impairment.

GP(TPAL)
Gravidity is the number of confirmed pregnancies. If multifetal → considered as 1.
Parity is the number of deliveries after 20 wk. If multifetal → considered as 1.
Abortus is the number of pregnancy losses (abortions) before 20 wk regardless of cause (e.g. spontaneous, therapeutic, or elective abortion; ectopic pregnancy).
Parity is often recorded as 4 numbers (TPAL):
number of term deliveries (> 37 wks)
number of premature deliveries (20-37 wks)
number of abortions (< 20 wks)
number of living children

Thus, a woman who is pregnant and has had one term delivery, one set of twins born at 32 wk, and 2 abortions is G5 P2 or G5 P2 (1-1-2-3).

Gestational age & EDD

Naegele's rule:
EDB = 1 yr - 3 mos + 7 days
However, if e.g. period = 30 d, then EDB = 1 yr - 3 mos + 9 d, etc.



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Perinatal Care

Weeks Gestation	Visit / Test	Comments
Up till 30 weeks	Routine visit every 4 weeks	At each routine visit the following are done: weight, BP, urine dipstick (protein & glucose), symphysis-fundal height, fetal position, fetal heart rate
30 to 36 weeks	Routine visit every 2 weeks
Beyond 36 weeks	Routine visit every week	may perform internal exam to assess dilation, effacement, etc.

Weeks Gestation	Visit / Test	Comments
Pre-conception	Folic acid supplementation, rubella status, varicella status	Folic acid helps prevent neural tube defects; rubella & varicella vaccines are given before pregnancy if not immune
1st Prenatal Visit	Prenatal screen, CBC, TSH. U/A, MSU, urine for chlamydia & N. gonorrhea. Pap smear.	E.g. to check for anemia, certain infections including HIV, and your blood type
15-16 weeks	Maternal serum screen (MSS) AFP: alpha-fetoprotein uE3: uncongugated estriol hCG: human chorionic gonadotropin DIA: dimeric inhibin-A PAPPA: pregnancy associated plasma protein A	To assess the risk for neural tube defects & trisomy
18 weeks	Ultrasound	To confirm due date, check on baby's health, & assess position of the placenta in the uterus
24-28 weeks	50 g oral glucose tolerance test	To screen for diabetes GDM screening Within 6 mos of delivery, women who had GDM should have FPG and/or 2hr PG in a 75g OGTT.
28 weeks	RhIg if Rh -ve	To prevent isoimmunization
36 weeks	GBS swab, RPR, Hb	To test for bacteria that could infect the baby during delivery
6 weeks post-partum	BP bleeding bladder function bowel function birth control breast feeding blues bimaual exam & Pap Hb, TSH

Expected weight gain during pregnancy is 13 kg (28 lbs).
During the early months, weight gain should be between 0.9 - 1.4 kg/mo.
Most women require about 250 kcal extra daily; most should come from protein. Weight-loss dieting during pregnancy is not recommended, even for morbidly obese women.

Most pregnant women need a daily oral iron supplement of ferrous sulfate 300 mg or ferrous gluconate 450 mg, which may be better tolerated. Woman with anemia should take the supplements bid.

All women should be given oral prenatal vitamins that contain folate 0.4 mg qd. Folate reduces risk of neural tube defects. For women who have had a fetus or infant with a neural tube defect, the recommended daily dose is 4 mg.

Pregnant women can continue to do moderate physical activities and exercise but should take care not to injure the abdomen. Sexual intercourse can be continued throughout pregnancy unless vaginal bleeding, pain, leakage of amniotic fluid, or uterine contractions occur.

The safest time to travel during pregnancy is between 14 and 28 wk. Travel on airplanes is safe until 36 wks gestation. Travel time should not exceed 5 hrs/day. Pregnant women should wear seat belts regardless of gestational dates and type of vehicle.

Vaccines for measles, mumps, rubella, and varicella should not be used.
Hepatitis B vaccine can be safely used if indicated.
Influenza vaccine is given in the 2nd or 3rd trimester during influenza season.

Avoid:

exposure to chemicals or paint fumes
direct handling of cat litter (due to risk of toxoplasmosis)
prolonged temperature elevation (e.g. in a hot tub or sauna)
exposure to people with active viral infections (e.g. rubella, parvovirus [fifth disease], varicella).

Seek medical attention if:

unusual headaches
visual disturbances
pelvic pain or cramping
vaginal bleeding (approx. 20-30% of pregnancies during 1st 20 wks; approx. 1/2 → spontaneous abortion).
rupture of membranes
extreme swelling of the hands or face (r/o DVT, preeclampsia)
diminished urine volume
any prolonged illness or infection

Drugs in pregnancy

Hypertensive disorders in pregnancy

Pathophysiology



1. There is no evidence that antihypertensive therapy for mild to moderate hypertension improves perinatal outcome.
2. Currently there are no therapies that effectively prevent pre-eclampsia.

   Classification
   

   	resistant htn, proteinuria, adverse conditions	none
   Htn at < 20 wks	pre-existing htn w preeclampsia	pre-existing htn
   Htn onset > 20 wks	gestational htn w preeclampsia	gestational htn w/o preeclampsia

   Resistant hypertension is an unexpected rapid rise in BP or requirement of ≥3 antihypertensive medications.

   Adverse conditions
   

   Vascular/Pulmonary: sBP ≥160 or dBP ≥ 110 Pulmonary edema Chest pain SOB (dyspnea)	HELLP syndrome: Hemolysis Elevated liver enzymes (AST, ALT, LDH) Low platelet count
   Renal: ↑ creatinine albumin < 20 g/L	Central nervous system: New, severe, or unusual headache Seizures (eclampsia) Visual disturbances (blurring, scotomata) Tremulousness, irritability, somnolence Hyperreflexia
   Hepatic: Elevated liver enzymes (AST, ALT, LDH) Abdominal/epigastric/right upper quadrant pain Severe nausea or vomiting	Fetal consequences of severe gestational hypertension: Assymetric IUGR Oligohydramnios Absent or reversed end diastolic umbilical artery flow Placental abruption Prematurity
   Hematological: Platelets < 100,000

   Lab tests	Possible results in HDP
   Hematologic
   Hemoglobin	↑ (dt hemoconcentration, unless microangiopathic hemolytic anemia)
   WBC and differential	neutrophilia
   Platelets	↓
   Blood film	Microangiopathy with RBC fragments
   INR & aPTT	↑ if DIC
   Fibrinogen	↓ if DIC
   Renal
   Creatinine	↑ (dt hemoconcentration and/or renal failure)
   uric acid	↑ (dt renal failure)
   Albumin	↓
   Proteinuria	↑
   Hepatic
   Glucose	Normal (low in acute fatty liver of pregnancy)
   AST	↑
   ALT	↑
   LDH	↑
   Albumin	↓
   Bilirubin	↑ (unconjugated from hemolysis, or conjugated from liver dysfunction)

Preeclampsia
Preeclampsia and eclampsia develop between 20 wk gestation and the end of the 1st wk postpartum.
Affects 3-7% of pregnant women, usually primigravidas and women with preexisting hypertension or vascular disorders (eg, renal disorders, diabetic vasculopathy). Other risk factors may include maternal age < 20, a family history of preeclampsia, preeclampsia or poor outcome in previous pregnancies, multifetal pregnancy, obesity, and thrombotic disorders (eg, antiphospholipid antibody syndrome).

Signs:

Edema. Nondependent edema such as facial or hand swelling is more specific than dependent edema.

Increased reflex reactivity, indicating neuromuscular irritability, which can progress to seizures (eclampsia).

Petechiae may reflect a bleeding tendency.

Tests:

CBC (including platelet count)
urate
AST, ALT, LDH
electrolytes, BUN, creatinine,
urinalysis
creatine clearance
24-hr urine protein

Diagnosis:

new-onset hypertension (BP ≥ 140/90 mm Hg) plus
unexplained proteinuria of ≥ 1+ on dipstick on 2 occasions at least 4 h apart after 20 wks gestation and
disappearing w/n 6 wks post-partum.

Tx:

Definitive treatment is delivery.

For pregnancies < 37 wk & if preeclampsia is mild:

outpatient treatment is possible
strict bed rest, lying on the left side whenever possible
normal salt intake
increased fluid intake
evaluation every 2 or 3 days

Labetalol 100-600 mg BID - QID, maximum daily dose 1200 mg

• Combined alpha-1 and ß-blocker with intrinsic sympathetic activity
• Rapid onset of action with both the intravenous and oral routes
• IV route particularly useful for hypertensive crisis although it may be administered orally, in hypertensive emergencies, with good effect.

Patients with mild eclampsia that does not immediately abate, severe preeclampsia, or eclampsia require hospitalization:

↓ BP to 140-155/90-105 mm Hg
then delivery

severe Preeclampsia

1. sBP > 160 or
   dBP > 105 &
   proteinuria (3+ dipstick or > 5g/d)
2. The rationale for antihypertensive treatment is to prevent maternal cerebrovascular accidents, not seizures.
3. Seizure prophylaxis, when indicated, should be with MgSO4.

Severe preeclampsia may cause organ damage; manifestations include headache, visual disturbances, confusion, epigastric or right upper quadrant abdominal pain (reflecting hepatic ischemia or capsular enlargement), nausea, vomiting, shortness of breath or dyspnea (reflecting pulmonary edema or acute respiratory distress syndrome [ARDS]), and oliguria (reflecting decreased plasma volume or ischemic acute tubular necrosis).

Labetalol

• bolus: 20 mg IV over 2 minutes, q 10 mins (maximum total dose of 300 mg)
• Infusion: 1-2 mg/minute and increase by 1 mg every15 minutes to a maximum of 4 mg/min

Hydralazine

10 mg IV q 20 mins (maximum total dose of 30 mg)
Patients with severe preeclampsia require Mg sulfate as soon as diagnosis is made. When delivery is delayed before about 32 to 34 wk in patients who are not clinically deteriorating, corticosteroids are given for 48 h. Delivery is mandated at 34 wk or when deterioration of maternal or fetal status or documentation of fetal lung maturity occurs.

If BP remains high after 8 wks postpartum, chronic hypertension should be considered.

Eclampsia

Unexplained generalized seizures in patients with preeclampsia.
Occurs in 1/200 patients with preeclampsia.

Eclampsia always requires delivery after seizures and severe hypertension have been controlled. All hospitalized patients are checked frequently for seizures, symptoms of severe preeclampsia, and vaginal bleeding. BP, reflexes, and fetal heart rate are monitored continuously or several times a day.


Mg sulfate 4 g IV over 20 min followed by a constant IV infusion of 1-3 g/hr.

Mg sulfate dose is adjusted based on the patient's reflexes, BP, and serum Mg levels (therapeutic range 4-7 mEq/L). Patients with excess Mg levels (eg, with Mg levels > 10 mEq/L or a sudden decrease in reflex reactivity) or hypoventilation are treated with Ca gluconate 1 g IV.

Mg sulfate may cause lethargy, hypotonia, and transient respiratory depression in neonates. However, serious neonatal complications are uncommon.

Bleeding in late pregnancy

placenta previa
RFs: multiparity, multifetal pregnancy, prior uterine surgery (particularly cesarean section), and other uterine abnormalities that can interfere with implantation (eg, fibroids).
Bright, large-volume vaginal bleeding with mild or minimal uterine pain suggests placenta previa.
abruptio placentae

RFs: prior abruptio placentae, maternal age > 35, multiparity, hypertension, tobacco use, substance abuse (particularly cocaine), abdominal trauma, maternal sickle cell anemia, thrombotic disorders, vasculitis, and other vascular disorders.
Dark, small-volume vaginal bleeding with moderate to severe uterine pain suggests abruptio placentae.
labor (with expulsion of a bloody mucus plug)
occult marginal placental separation
previously asymptomatic cervical and vaginal lesions (e.g. polyps, ulcers) often bleed for the 1st time because pelvic blood flow increases during late pregnancy

Pregnancy-induced vomiting

Nausea and vomiting during pregnancy are thought to occur because estrogen levels increase rapidly. They are most common and severe during the 1st trimester.
Hyperemesis gravidarum is persistent pregnancy-induced vomiting that causes significant dehydration, often with electrolyte abnormalities or ketosis.

5 or 6 small meals/day of bland foods (eg, crackers, soft drinks, BRAT diet [bananas, rice, applesauce, dry toast]) should be eaten.

Meds:


diclectin (doxylamine/vit B6) 2 tbs q.hs. prn
+/- 1 tab q. AM & q. mid PM prn

doxylamine 10 mg po at bedtime
metoclopramide 10 mg po or IV q 8 h prn
ondansetron 8 mg po or IM q 12 h prn
promethazine (PHENERGAN) 12.5 to 25 mg po, IM, or rectally q 6 h prn
pyridoxine (vitamin B6) 10 to 25 mg po tid prn

Rh0(D) immune globulin

prophylactically at 28 wks
after delivery if the neonate is Rh-positive
Rh-negative women are given Rh0(D) immune globulin 300 μg IM :
after any significant vaginal bleeding or other sign of placental hemorrhage or separation (abruptio placentae)
after a spontaneous or therapeutic abortion
after amniocentesis or chorionic villus sampling

Beginning of labor

Bloody show (a small amount of blood with mucous discharge from the cervix) may precede onset of labor by as much as 72 h.
Bloody show can be differentiated from abnormal 3rd-trimester vaginal bleeding because the amount is small & is typically mixed with mucus, and the pain due to abruptio placentae is absent.
In most pregnant women, previous ultrasonography has ruled out placenta previa. However, if ultrasonography has not ruled out placenta previa and vaginal bleeding occurs, placenta previa is assumed to be present until it is ruled out. Digital vaginal examination is contraindicated, and ultrasonography is done as soon as possible.

1st stage of labor

From onset of labor to full dilation of the cervix (about 10 cm).
2 phases, latent and active.

During the latent phase, irregular contractions become progressively better coordinated, discomfort is minimal, and the cervix effaces and dilates to 4 cm.


Pelvic examinations are done every 2 to 3 h to evaluate labor progress. Lack of progress in dilation and descent of the presenting part may indicate dystocia (fetopelvic disproportion).

Women may begin to feel the urge to bear down as the presenting part descends into the pelvis. However, they should be discouraged from bearing down until the cervix is fully dilated so that they do not tear the cervix or waste energy.

Amniotomy
If the membranes have not spontaneously ruptured, some clinicians use amniotomy (artificial rupture of membranes) routinely during the active phase. As a result, labor may progress more rapidly, and meconium-stained amniotic fluid may be detected earlier. Amniotomy during this stage may be necessary for specific indications, such as facilitating internal fetal monitoring to confirm fetal well-being.

Amniotomy should be avoided in women with HIV infection or hepatitis B or C, so that the fetus is not exposed to these organisms.

2nd stage of labor

From full cervical dilation to delivery of the fetus.

On average, it lasts 2 h in nulliparas (median 50 min) and 1 h in multiparas (median 20 min).

It may last another hour or more if conduction (epidural) analgesia or intense opioid sedation is used.

For spontaneous delivery, women must supplement uterine contractions by beginning to expulsively bear down.

In the 2nd stage, women should be attended constantly, and fetal heart sounds should be checked continuously or after every contraction.

3rd stage of labor

Begins after delivery of the infant and ends with delivery of the placenta.

Begins after delivery of the placenta.

Dilation: 10 cm is considered complete.
Effacement is estimated in percentages, 0-100%. Effacement involves cervical shortening as well as thinning. The normal, uneffaced average cervical length is 3.5-4.0 cm.
Station is expressed in centimeters above or below the level of the maternal ischial spines. Level with the ischial spines corresponds to 0 station; levels above (-) or below (+) the spines are recorded in cm increments.
Presentation describes the part of the fetus at the cervical opening (eg, breech, vertex, shoulder).
Position describes the relationship of the presenting part to the maternal pelvis (eg, occiput left anterior [OLA] for cephalic, sacrum right posterior [SRP] for breech).
Lie describes the relationship of the long axis of the fetus to that of the mother (longitudinal, oblique, transverse)
Attitude describes the relation of various parts of the fetal body to one another.

Active management of labor

Labor is diagnosed when painful contractions are accompanied by complete cervical effacement, bloody "show," or ruptured membranes. Women with such findings are committed to delivery within 12 hours.

Pelvic exam each hour for the next 3 hours, and thereafter at 2-hour intervals.

If dilatation not ↑ > 1 cm/hr → amniotomy

Pelvic exam 2 hrs later. If dilatation not ↑ > 1 cm/hr → high-dose oxytocin infusion started.

Oxytocin 10 u in 1 L D5W regulated by a personal nurse. The total dose may not exceed 10 units and the infusion rate may not exceed 30 to 40 mU/min.

Induction of labor

High priority:

Severe pre-eclampsia
Significant maternal disease not responding to treatment
Significant, but stable, antepartum hemorrhage
Chorioamnionitis
Suspected fetal compromise
Term PROM with group B streptococcus colonization

Other indications:

Post-dates
Prevention of post-dates
Diabetes mellitus (the quality of glycemic control may dictate urgency)
Pre-eclampsia ≥ 37 wks
Alloimmune disease at or near term
IUGR
PROM at or near term (GBS culture negative)
Intrauterine fetal death
Logistical problems (e.g., history of rapid labour, distance to hospital)


Contraindications:

Any contraindication to labour
Placenta previa or vasa previa
Cord presentation
Abnormal fetal lie or presentation (e.g., transverse lie or footling breech)
Prior classical or inverted T incision Caesarean section
Significant previous uterine surgery (i.e., full thickness myometrial incision)
Active genital herpes infection
Pelvic structural deformities (e.g., history of a pelvic fracture)
Invasive cervical carcinoma
Previous uterine rupture


Sweeping or 'stripping' the membranes may promote the onset of labour by increasing local production/release of prostaglandins. When membrane sweeping is performed in women at term, it is associated with a reduced duration of pregnancy and reduced frequency of pregnancy continuing beyond 41 weeks.

Modified Bishop Score

Score	0	1	2
Dilation (cm)	0	1-2	3-4
Effacement	30%	50%	70%
Length (cm)	> 3	2	< 1
Consistency	Firm	Medium	Soft
Position	Posterior	Mid	Anterior
Station (cm)	-3 or above	-2	-1 or lower

The condition of the cervix at the start of induction is an important predictor of success. The modified Bishop score is out of 10. The most important element is dilation followed by effacement, station, and position. A Bishop score of < 4 have significantly higher rates of failed induction.

Options for cervical ripening and induction of labour with an unfavourable cervix
Foley catheter
Hydroscopic dilators (laminaria/artificial tent)
Dinoprostone (Prepidil®) 0.5mg into the cervical canal
Dinoprostin (Prostin®) 1-2 mg into the posterior fornix
Dinoprostin (Cervidil®) 10 mg into the posterior fornix


Options for induction of labour with a favourable cervix

Amniotomy
Oxytocin (usually clinical response at 8-12 mU/min at term. Water intoxication possible if >40 mU/min. No direct effect on cervix. Half-life is approximately 5 mins)

Reactive nonstress test: FHR ↑ > 15 bpm for > 15s following fetal movements (indicated by vertical marks).

Biophysical profile

Component	Score 2	Score 0
Nonstress testa	³ 2 accelerations of ³ 15 beats/min for ³ 15 sec in 20-40 min	0 or 1 acceleration in 20-40 min
Fetal breathing	³ 1 episode of rhythmic breathing lasting ³ 30 sec within 30 min	< 30 sec of breathing in 30 min
Fetal movement	³ 3 discrete body or limb movements within 30 min	< 3 discrete movements
Fetal tone	³ 1 episode of extension of a fetal extremity with return to flexion, or opening or closing of hand within 30 min	No movements or no extension/flexion
Amnionic fluid volumeb	Single vertical pocket> 2 cm	Largest single vertical pocket £ 2 cm

aMay be omitted if all four ultrasound components are normal. bFurther evaluation warranted, regardless of biophysical composite score, if largest vertical amnionic fluid pocket £ 2 cm.

Fetal monitoring

Interpretation of FHR
(Small square=10 seconds; large square=one minute)

Nonreassuring patterns: (→ scalp pH)

tachycardia (e.g. infection, drugs, ↑ thyroid, tachyarrhthymia, prematurity)
bradycardia (e.g. hypoxia, mat'l collagen vasc dz))
saltatory variability (e.g. umbilical cord compression)
nonreassuring variable decelerations (e.g. hypoxia)
late decelerations with preserved beat-to-beat variability
Ominous patterns: (→ immed delivery)
persistent late decelerations with loss of beat-to-beat variability
variable decelerations associated with loss of beat-to-beat variability
prolonged severe bradycardia (<80 bpm)
sinusoidal pattern (e.g. severe anemia or hypoxia)
confirmed loss of beat-to-beat variability not associated with fetal quiescence, medications, or severe prematurity




Normal pattern:
(reassuring)



120 to 160 bpm at baseline
Preserved beat-to-beat and long-term variability
Varies by 6-25 bpm with movement or contractions
Accelerations last > 15 s & peak at > 15 bpm above baseline
No decelerations during contractions

Early decelerations: head compression
(reassuring)



Onset and return of deceleration coincides with start and end of contraction, giving the characteristic mirror image
Preserved beat-to-beat and long-term variability
Varies by 6-25 bpm with movement or contractions
Accelerations last > 15 s & peak at > 15 bpm above baseline
No decelerations during contractions

Variable decelerations: umbilical cord compression
(nonreassuring)



Rapid downslope and a variable recovery phase
Characteristically variable in duration, intensity, and timing
Pre- and post-accelerations ("shoulders")
Beat-to-beat variability preserved

Late decelerations: uteroplacental insufficiency (caused e.g. by maternal hypotsn, uterine hyperstim)
(nonreassuring)



Onset at the peak of the uterine contraction
Return to baseline after the contraction has ended

Emergency Interventions for Nonreassuring Patterns

Call for assistance

O2 with tight-fitting face mask

Lateral or knee-chest posn

Fluid bolus (lactated Ringer's solution)

Vaginal exam & fetal scalp stimulation

When possible, determine and correct the cause

Discontinue oxytocin if used

Consider tocolysis (for uterine tetany or hyperstimulation)

Consider amnioinfusion (for variable decelerations)

Determine whether operative intervention is warranted

Pre-labor rupture of membranes (PROM)

Rupture of the membranes before onset of labor.

PROM at any time increases risk of chorioamnionitis, neonatal sepsis, prolapse of the cord; and fetal complications, such as abnormal joint positioning.

Sterile speculum examination is done to verify PROM, estimate cervical dilation, collect amniotic fluid for culture and fetal maturity tests, and obtain cervical cultures.

Diagnosis is assumed if amniotic fluid appears to be escaping from the cervix or if fetal vernix or meconium is visible.

Other less accurate indicators include vaginal fluid that ferns when dried on a glass slide or turns Nitrazine paper blue (indicating alkalinity, normal vaginal fluid is acidic).

Some clinicians routinely induce labor when gestational age is > 34 wk.

Corticosteroids should be given to accelerate fetal lung maturity in pregnancies < 32 wks. Their use between 32 and 34 wk is controversial.

Occurs before 37 wks.

Predisposes to preterm labor.

Preterm labor

Labor that begins before 37 wk gestation.

Triggers:
May be triggered by PROM, chorioamnionitis, or other ascending uterine infection (group B streptococci are the most common cause), multifetal pregnancy, preeclampsia or eclampsia, placental abnormalities, pyelonephritis, or some sexually transmitted diseases. Cervical culture are done to check for causes suggested by clinical findings.

Fetal fibronectin (fFN)

fFN is produced at the uteroplacental (choriodecidual) junction. fFN should not be detectible between 22 and 36 wks. Elevated levels during this period reflect a disturbance at the uteroplacental junction and have been associated with an increased risk of preterm labor.

A Dacron swab is used to take a sample of fluid from the posterior portion of the vagina.

fFN should only be used if:

Intact membranes
Cervix < 3 cm dilated
Only slight vaginal bleeding
No cervical cerclage
Sexual intercourse or a pelvic examination within 24 hrs may give a false positive result.

Management
Bed rest, hydration, and antibiotics may be sufficient Tx.

Antibiotics effective against group B streptococci are given unless there are negative cervical cultures. Choices include:

Penicillin G 5 million units IV followed by 2.5 million units q 4 h
For penicillin-allergic patients: Clindamycin 900 mg IV q 8 h.

If the cervix dilates, tocolytics can usually delay labor for at least 48 h.

Mg sulfate is the drug of choice and is well tolerated.
Terbutaline 0.25 mg sc (which may be repeated once in 30 min) is given q 4 h until contractions cease; maximum, 0.5 mg/4 h. Maintenance with oral terbutaline is not effective.

If the fetus is < 34 wks → corticosteroids:

Betamethasone acetate suspension 12 mg IM q 24 h for 2 doses or
Dexamethasone 6 mg IM q 12 h for 4 doses unless delivery is imminent.

These corticosteroids accelerate maturation of the fetal lung and decrease risk of neonatal respiratory distress syndrome, intracranial bleeding, and mortality.


Lecithin-sphingomyelin (L/S) ratio begins to rise at about 34 weeks. The risk of neonatal respiratory distress is slight whenever the L/S > 2. Caution: blood has an L/S ratio of 1.3 to 1.5, and meconium usually lowers the L/S ratio.

Phosphatidylglycerol in amnionic fluid provides more assurance, but not an absolute guarantee, that respiratory distress will not develop. Because it is absent in blood, meconium, & vaginal secretions, these contaminants do not confuse its interpretation.

Postdatism is pregnancy of ≥ 42 wk.
Increased risk of abnormal fetal growth, oligohydramnios, meconium in amniotic fluid, and fetal death.
Most experts recommend that nonstress testing and assessment of amniotic fluid volume, or a biophysical profile (eg, assessment of amniotic fluid volume, fetal movement, breathing, and heart rate) be done at 41 wk. If abnormal, delivery is required. Many obstetricians induce labor.

Cardinal movements in parturition

1st-degree
Involve the fourchette, perineal skin, and vaginal mucous membrane but not the underlying fascia and muscle.

2nd-degree
Involve, in addition to skin and mucous membrane, the fascia and muscles of the perineal body but not the anal sphincter. These tears usually extend upward on one or both sides of the vagina, forming an irregular triangular injury.





A. Chromic 2-0 or 3-0 suture is used as a continuous suture to close the vaginal mucosa and submucosa.
After closing the vaginal laceration & the margins of the hymenal ring, the suture is tied and cut.

B. 3-4 interrupted sutures of 2-0 or 3-0 chromic are placed in the fascia and muscle of the incised perineum.

C. A continuous suture is carried downward to unite the superficial fascia.

D. The continuous suture is carried upward as a subcuticular stitch.

3rd-degree
Extend through the skin, mucous membrane, and perineal body, and involve the anal sphincter.

4th-degree
Extends through the rectal mucosa to expose the lumen of the rectum.

Shoulder dystocia

A Ask for help
L Lift / hyperflex legs (McRoberts maneuvre)
A Anterior shoulder disimpaction (suprapubic pressure)
R Rotate posterior shoulder
M Manual removal posterior arm
E Episiotomy
R Roll over onto 'all fours'

McRobert's maneuvre
Flatten head of the bed & hyperflex both legs (successful in 42% of cases)


Anterior disimpaction - suprapubic approach Suprapubic (not fundal) pressure is applied with the heel of clasped hands from the posterior aspect of the anterior shoulder to dislodge it (Mazzanti maneuver). Apply a steady pressure first and, if unsuccessful, apply a rocking pressure.

Anterior disimpaction - vaginal approach Adduction of the anterior shoulder (Rubin maneuvre).

Woods' maneuvre
Pressure is applied to the anterior aspect of the posterior shoulder. The anterior disimpaction maneuvre and Woods' maneuvre may be done simultaneously and repetitively.


Manual removal of the posterior arm
The hand is grasped, swept across the chest and delivered. This may lead to humeral fracture, which does not cause permanent neurological damage.


Roll over to "all fours" position
This increases the effective pelvic dimensions and allows the fetal position to shift. This may free the impacted shoulder. With gentle downward pressure on the posterior shoulder, the anterior shoulder may become more impacted (with gravity) but will facilitate the freeing up of the posterior shoulder. This position may also allow easier access to the posterior shoulder for rotational manoeuvres or removal of the posterior arm. This maneuvre may be considered earlier in the management of shoulder dystocia.

Call for assistance
Perform a pelvic examination to determine:
effacement, dilation, & station
presence of pulsations within the cord
Elevate the presenting part & maintain the elevation until delivery
Place the woman in the knee-chest or Trendelenburg position (it may be acceptable to elevate the woman’s hips as opposed to placing the bed in Trendelenburg)
Do not attempt to replace the cord. Keep the cord warm if it is outside of the vagina (e.g., warm, saline-soaked cloth).
O2
Prepare for immediate Caesarean section

3rd stage

Use of uterotonics such as oxytocin may be given as:
10 U IM or
20 U in 1000 ml normal saline IV infusion (100–150 cc/hour)

Wait for signs of placental separation (vaginal bleeding or laxity of the umbilical cord). Maintain tension on the cord by pulling gently while applying suprapubic counter-traction on the uterus. Pulling hard on the cord may cause the cord to avulse or result in uterine inversion.

Consider waiting 1-2 mins before clamping the cord
If the placenta has not delivered after approximately 15 mins and oxytocin has not already been administered, give it at this time. The mean duration of the third stage is 8 to 10 mins. After 30 minutes the risk of PPH is 6x normal.

Tone - uterine atony (most common and important cause of PPH)
Tissue - retained placenta or clots
Trauma - uterine, cervical or vaginal injury
Thrombin - pre-existing or acquired coagulopathy


Bimanual massage

Oxytocin (1st line):

oxytocin 5 U IV bolus
oxytocin 20-40 U in 1 L normal saline, initially wide open
oxytocin 10 U intramyometrially if there is cardiovascular collapse or no IV access.

If the uterus is still boggy and has not been explored, this must be done now in order to rule out retained clots or products, uterine rupture or inversion.

If bogginess or hemorrhage continues, consider any of the following agents:

prostaglandin F2α (Carboprost/Hemabate) 250 μg IM or intramyometrially q15mins (maximum cumulative dose 2 mg). Asthma is a relative contraindication

ergonovine (Ergometrine)0.2 mg IM or IV q5mins (maximum cumulative dose 1.5 mg)
contraindicated in hypertensive disorders of pregnancy because of the risk of stroke or a hypertensive crisis; contraindicated with concomitant use of certain drugs used to treat HIV (e.g., protease inhibitors, non-nucleoside reverse transcriptase inhibitors)

If repeated doses of any of these medications are insufficient, an alternate plan is necessary.